Historically, people have not been overly concerned about the fact that some of the petroleum storage tanks have leaked and/or that there have been minor spills. Unfortunately, the number of minor spills that occurred in places, such as service stations or vehicular repair facilities to mention two, have been cumulative, such that the soil surrounding the facility and/or tanks have become saturated or close thereto. There is a current concern, compounded by our more realistic assessment of damage done by these spills, as to the long-term effect upon health, such as through the contamination of ground water or the like.
Up until this point in time, the primary approaches that have been taken to the petroleum contamination problem have included farming the soil, i.e. placing it in a fallow field and turning it allowing the volatiles to evaporate and escape into the atmosphere, not necessarily a viable alternative or subjecting the soil to extremely high heat and/or agitation over a long and tortuous path to drive off the volatiles, and then either filter the escaping air or subject it to high temperatures to ignite the material driven off.
Examples of apparatus and methods used for cleaning contaminated soil and/or reducing other contaminants are shown in the prior art noted during a preliminary patentability search include:
U.S. Pat. No. 3,570,420 granted to Lewis, et al, Mar. 16, 1971, which discloses an apparatus for removal of the hydrocarbon content of cuttings from subterranean wells by combustion.
U.S. Pat. No. 4,009,667 granted to Tyer, et al, on Mar. 1, 1977, discloses an incinerator wherein combustible refuse is carried through a combustion chamber by means of a variable speed auger, and a portion of the exhaust gas is recirculated to preheat the entering refuse.
U.S. Pat. No. 4,202,282 granted to Hobbs, et al, on May 13, 1980, discloses a method and apparatus for processing sewage sludge through the use of infrared radiation under a slight vacuum to capture the noxious odors.
U.S. Pat. No. 4,231,304 granted to Hoskinson on Nov. 4, 1980 discloses a waste combusting apparatus including a hollow auger through which air is forced to improve combustion. Secondary combustion is provided with respect to the waste gases.
U.S. Pat. No. 4,337,711 granted to Bolton, Jul. 6, 1982, discloses a method and apparatus for the combustion of petroleum wastes wherein the wastes are mixed with combustible solids, such as wood chips, and then the mixture is incinerated.
U.S. Pat. No. 4,338,869 granted to Hoskinson, Jul. 13, 1982, discloses a combustion apparatus, including a hollow auger through which air is forced to improve the combustion.
U.S. Pat. No. 4,342,269 granted to Hoskinson, Aug. 3, 1982, discloses an incinerator having a hollow auger for transporting the material to be burned and for transporting air to improve the combustion and also including a means to cool the auger.
U.S. Pat. No. 4,357,152 granted to Duske, et al, Nov. 2, 1982, discloses a particulate separator which uses an interior configuration of a tapered cylinder to increase the turbulence to assist in the separation.
U.S. Pat. No. 4,558,525 granted to Duske, et al, Dec. 17, 1985, discloses a rotary drying system for particulate material utilizing differently configured cylinders to increase the turbulence and promote efficient drying.
U.S. Pat. No. 4,648,332 granted to Goodhart, Mar. 10, 1987, discloses a method of cleaning contaminated soil by subjecting it to heat in a combustion chamber including a fluidized bed.
U.S. Pat. No. 4,648,333 granted to Mudd, et al, Mar. 10, 1987, discloses a method for treating oil field wastes containing hydrocarbons, wherein fuel and pressurized air are inserted into the furnace, wherein the hydrocarbons are burned utilizing the hydrocarbons as a source of combustion for its treatment.
U.S. Pat. No. 4,667,609, granted to Hardison, et al, May 26, 1987, discloses an apparatus for the treatment of soil contaminated with hydrocarbons, including a sealed negatively pressurized high temperature furnace wherein the multizone heater is maintained at about 2900.degree. F.
U.S. Pat. No. 4,815,398 granted to Keating, II, et al, Mar. 28, 1989, discloses an apparatus and method for detoxifying soils, including an apparatus for heating the material to a first temperature to volatilize the volatile organic compound which is then heated to destroy the organics, and this volatile rich gas is used as fuel for heating a kiln.
U.S. Pat. No. 4,870,911 granted to Chang, et al, Oct. 3, 1989, discloses an incinerator pyrolyzer for continuously burning waste material in a rotating kiln.
U.S. Pat. No. 4,881,475 granted to DeLeur, Nov. 21, 1989, discloses a method for cleaning contaminated soil through the use of heated wall of a rotating furnace.